1. Field of the Invention
The present invention relates to a waterproofing agent for ink jet printing paper. In particular, the invention relates to a waterproofing agent for ink jet printing paper which is able to improve the water resistance of images and characters printed on printing paper, eliminate virtually all color tone change, eliminate virtually all yellowing of blank sections, and give printing paper with low ink blotching, when it is mixed with pulp fiber into a slurry for sheet making, or impregnated or coated onto plain paper or coated paper.
2. Description of the Related Art
Ink jet printing is characterized by requiring no step of development and fixation, employing simple printing apparatuses and using plain paper or coated paper, while also facilitating coloring and allowing both printing of images and character graphics, and for these reasons it is rapidly becoming more widely used and is expected to be useful in the future. When plain paper is used for ink jet printing, problems generally occur such as blotching of the dye upon contact with moisture after printing, and therefore the use of waterproofing agents has been investigated. Known waterproofing agents include cationic resins such as dicyandiamide condensates, polyamines and polyethyleneimines, but these have presented such problems as poor water resistance, color tone changes, yellowing of blank areas and ink blotching, and therefore waterproofing agents have been sought which have satisfactory water resistance, and which produce no change in color tone or yellowing of blank areas, and no ink blotching.